Palestine campaigners have chained the doors shut and are occupying the roof of an arms factory in Shenstone in Staffordshire that is owned by an Israeli military company and manufactures engines for drones that have been exported to Israel.

At around 5am, a group of 12 activists from the London Palestine Action network chained shut the main gates to the factory and scaled the 8m roof. The group are now staging an occupation of the rooftop with the intention of closing the factory.

In 2009, Amnesty International pointed to evidence that engines from the factory were used in Hermes 450 drones that have been documented as documented as being used to deliberately attack and kill civilians during the 2008-09 Operation Cast Lead attack on Gaza.

The occupation comes the day after the UK government pledged to investigate whether any of £8bn of arms exported to Israel in the last 5 years are being used in Israel's ongoing attacks on Palestinians in Gaza.

One of the occupiers, Sara Cooper, 26, a teacher from south London said:

"By allowing this factory to export engines for killer drones to Israel, the UK government is providing direct support and approval to Israel's massacres."

"The UK government has blood on its hands and must end its support for Israel's crimes against humanity by ending all forms of military cooperation with Israel, starting by closing this factory. We demand the UK government stop arming Israel."

"Israel is only able to murder Palestinian civilians in cold blood and attack UN schools and hospitals because of the huge military cooperation it enjoys with companies and governments around the world. This factory is the clearest example of the vast military cooperation taking place between the UK and Israel."

The factory is also a key part of the £1bn Watchkeeper program under which Elbit Systems is leading the manufacture of a new generation of drones for the UK military. The Watchkeeper drone is based on the Hermes 450, documented as being used to kill Palestinian civilians during the 2008-09 attack on Gaza.

Cooper added:

"Elbit Systems markets its drone technology as 'battle tested', a sickening boast that their drones have been proven to be effective at killing Palestinians. The UK government is importing technology that has been developed during the course of Israel's crimes against humanity."

Since the beginning of the ongoing Israeli military assault of Gaza Elbit shares have climbed 6.1 percent. According to Bloomberg BusinessWeek, Israel's attack "has pushed [Elbit's] stock close to the highest level since 2010 while its valuation on a price-to-earnings basis is near the most expensive in five years."